The invention relates to the field of dynamoelectric machines and is applicable for the constructive configuration of the rotor of an asynchronous induction motor which has windings configured as conductor bars and short-circuited by end rings.
A conventional asynchronous machine of this type has a rotor core of massive steel whereby the rotor surface facing the air gap is formed with slots which have slot walls respectively converging outwardly in radial direction. The winding associated to the rotor is configured as squirrel-cage winding and is made of metallic conductor bars which are arranged form-fittingly in the rotor slots. The portions of the metallic conductor bars, disposed outside the laminated core of the stator, form together an assembled ring-shaped winding part, whereby these portions are suitably welded together. As the conductor bars are configured as U-shaped bars, with each U-leg filling half of a rotor slot, the squirrel-cage winding projects partly into the magnetic air gap (DE 2 537 706 B1).
The rotor core of another known asynchronous machine is made of metal sheets provided with recesses for receiving conductor bars. The conductor bars have ends associated to short-circuit rings which are soldered to the ends of the conductor bars (DE 2 362 195 A1).
In order to achieve an asynchronous machine of great power and high operating speed, a rotor construction is further known having a rotor core made of metal sheets and associated to a pre-fabricated squirrel cage which is made of two half-cages with attached short-circuit rings which are welded or soldered together approximately in the area of half the length of the short-circuit rotor. Suitably, capping retaining rings of high-strength, non-magnetic material are hereby additionally placed over the short-circuit rings (DE 197 29 432 C1).